This invention relates to electric heaters, and in particular to a structure for supporting heating elements or coils in an electric heater such as an open coil beater. The present invention also includes methods for making such a support structure. While the invention is described with particular reference to open coil heaters, those skilled in the art will recognize the wider applicability of the inventive principles disclosed hereinafter. For example, this invention finds application in the heating and air conditioning field, and is useful in devices such as heat pumps, fan coil units, or combined heating and cooling air conditioners.
Open coil electric heaters typically include structures that support heating elements in a stacked or spaced parallel relationship with respect to other coils in the heater. The heating elements are operably connected to a terminal box assembly including control circuitry that selectively energizes the heating elements. Often separate support structures are used to individually position each heating element within the heater. Alternatively, complex support structures have been designed that can support multiple coils within the heater. Construction and assembly of such support structures typically require complicated and expensive manufacturing procedures, and involved installation procedures that further add to the cost of the heater. For example, each support structure typically includes a plurality of brackets having one or more heating coils threaded through openings formed therein. Construction of support structures employing such brackets increases manufacturing costs since the brackets are positioned axially along a support rail, and then individually attached to the rail.
Therefore, it is desirable to design a support structure for a multicoil heater that minimizes manufacturing and installation costs. Preferably, the support structure is constructed from a single piece of sheet metal, thereby requiring a minimal number of components and allowing for a high level of automation during manufacture and assembly of the unit. This construction also should be able to withstand heat stress and vibrations to which the support structure may be exposed during transportation, assembly and operation, as well as high terminal box ambients generated by abnormal conditions. It is further desirable that the coils can be easily threaded through the support structure. Additionally, the support structure should be readily mounted in the heater assembly to permit simple connection of the heating coils to the control circuitry.